Polar locking circuit



Oct. 17, 1950 A. E. CANFORA POLAR LOCKING CIRCUIT Filed May 12, 1945our/=07 WZN .l' 5/6/5441. I i WPUT :EOUTPUT iii INVENTOR. Aer/m f.CA/VFORA BY Patented Oct. 17, 195

2,526,003 POLAR LOCKING omourr Arthur E. Canfora, Brooklyn, N. Y.,assignor td Radio Corporation of America, a corporation of DelawareApplication May 12, 1945, Serial No. 593,502

2 Claims.

This invention relates to locking circuits.

More particularly my invention relates to a circuit arrangement of thetype which employs a triode discharge tube and a pentode discharge tubesuitably interconnected so that the triode tube may be held conductingor non-conducting by varying its grid voltage while the pentode tube iscontrolled by varying its screen grid voltage between positiveandnegative values. The controlling input signal is preferably appliedto the control grid of the pentode tube, either directly or through asuitable condenser. i

Locking circuits as heretofore known commonly employ two voltagedividers, one connected from the anode of a first tube to a point ofpotential below the cathode of the second tube, a tap being taken off ofthis voltage divider and connected to the control grid in the secondtube. The second voltage divider is like the first except that it isconnected between the anode of the second tube and a potential belowthat of the cathode in the first tube. A tap on this second voltagedivider is connected to the control grid of the first tube. In such anarrangement the ohmic values of the resistors involved in the voltagedividers must be held within a close percentage of the prescribed valuesif the proper circuit operation is to be obtained. This fact, therefore,necessitates the anticipation of any temperature changes to beencountered under operating conditions.

In the conventional locking circuit both anodes L wherein a pentode tubeand a triode tube are used,

in combination with suitable circuit components for carrying outtheinvention.

Referring to the drawing, I show therein a pentode discharge tube l anda triode discharge. In the pentode tube I show a cathode 3 connected toground, a control grid G to which.

tube 2.

signal input voltages may be applied, a screen grid 5 and a suppressorgrid 6, the latter being.

connected directly to the cathode 3.

The anode l of the tube I is connected through an anode resistor 8 tothe positive terminal of a In order to overcome the difiicultiesheretofore encountered as indicated in the foregoing paragraphs, I havefound it possible to design a looking circuit having only one voltagedivider, the respective values of its sections being less critical forproper operation of the circuit than was heretofore considerednecessary.

I also have found it possible to obtain two sets of outputs from theanodes, one set of which varies between potentials which are above belowthe common ground potential. I

It is, therefore, an objectof my invention to provide a simply designedlocking circuit having features which relieve it from the necessity forcritical adjustment of its components.

It is also an object to obtain an output which varies from a point aboveto a point below the common ground potential.

It is another object of my invention to provide a dependable polarlocking circuit for use in signaling and in other applications.

My invention will now be described in more detail, reference being madeto the accompanying drawing the sole figure of which representsillustratively a preferred circuit arrangement and tentials, one ofwhich direct current source, one section of which is indicated atS.Another section of this source I0 is in series with section 9 and hasits negative ter minal connected to ground.

In the tube 2, I show a cathode H, a control grid l2 and an anode 13.The cathode l l is maintained at a negative potential with respect toground, the bias voltage being suppiiedby a direct current source 14.Another biasing source I5 is connected between the cathode Ii and thecontrol grid [2, a resistor l6 being interposed between the negativeterminal of the source l5 and the grid l2. The grid i2 is also connectedto the anode l in tube I through. a resistor ll. The two resistors 16and I1 constitute a voltage divider which provides interaction betweenthe pentode tube and the triode tube.

The anode I3 is connected through a resistor It to the junction betweenthe two direct current source sections 9 and Ill. The anode I3 is alsodirectly connected to the screen grid 5 in tube l.

Shown also are output terminals i9 and 20. Terminal i9 varies betweentwo potentials above ground while terminal 20 varies between two poisabove and the other below ground.

Before proceeding with an explanation of how the circuit operates, itshould be pointed out that one of the well known characteristics ofpentode tubes is that even with a negative screen voltage the tube maystill be rendered conductive, provided the control grid is drivensufiiciently positive with respect to the cathode. The anode of course,must be maintained at a positive potential in order to produce aconductive state.

I will now show why it is unnecessary to fix the values of therespective elements 16 and ll with great exactitude in order to maintainsuitable operating conditions for the circuit. The diiferent kinds ofoutputs from the two anodes will also be explained.

Assume first that tube l is normally conductive in the absence of asignal potential. The voltage drop through the voltage divider #1, i6 issuch as to maintain a negative voltage on grid [2 inthe trio-de tube 2so that this tube is biased to cutoff, especially since a negativegridbias. is afforded by the C-battery [5. The anode l3 and the screen grid5, being interconnected, are both maintained at a relatively highpositive potential. The conductive state in tube I and thenon-conductive state in tube 2 may, therefore, be said to be relativelystable.

This condition makes available two different anode voltages. One fromanode l is the direct current source lD-l-S minus the IpRfl drop in 9where I1) is the pentode tube current. subtracted from 3+9 is also IdRiwhere Id is the current flowing through the divider i0, H. The otheroutput from anode I3 is the direct current source 10 minus IsRlS whereIs is the pentode screen current. Both of these outputs are at apotential above ground.

Now assume that a signal potential is applied in suificient magnitudeand negatively to the control grid 4 with respect to the groundedcathode 3. The pulse so applied need be of only momentary duration inorder to reverse the conductive states in the two tubes. Tube 1 beingnow blocked, its anode voltage rises substantially to the voltage at theposit ve terminal of the source 9. A positive increment of voltage is,therefore, applied to the control grid I2 in the triode tu e 2 which issufiicient to render the grid i2 more positive than the cathode N. Thisdrives the tube 2 conductive and at the same time lowers the screen gridvoltage 5 in tube i. In this state the potential of the anode i3 and ofthe screen grid 5 is so far reduced that it is negative with respect toground. This negative screen potential prevents tube from conducting.

In this condition the out uts are as fol ows: Terminal i9 is at apotential eoual to the direct current sources 9+"! minus the IdRS dropin resistor 8, and the terminal 20 is at a potential equal to the directcurrent source E minus the l'zPuia drop, where I2 is the triode platecurrent. This output potential is actua ly more negat ve than groundwhile the output at terminal 19 is above ground.

The locking circuit as herein shown and described the efore fulfills thefollowing conditions: The potential of the anode 7 in tube is shiftedbetween two posit ve va ues with respect to a certain referencepotential, while the anode H3 in tube 2 is shited from positive tonegati e values with respect to such a reference potential.

It should be understood that the input control signal could be appliedto the grid :12 in the triode tube 2 if so desired. In fact, controll ngsignals of the same polarity could be applied alternately to grids 4 and12 in the pentode and triode tubes res ectively.

Mv invention is capable of modification in various ways, as will be wellunderstood by those skill d in the art.

I claim:

1. In a locking circuit, two electron discharge tubes at least one beingof the multi-grid tyne with a screen grid and both having a. controlgrid, a cathode and an anode, a first direct current potential sourceconnected between the anode and cathode of said multi-grid tube, animpeder in said connection between the anode of the multi-' grid tubeand said source, a second direct current potential source of lesspositive value connected between the anode and cathode of the othertube, an impeder in said connection between the anode of the other tubeand said second source, a connection between the cathode of saidmulti-grid tube and a point on said second source which is positive withrespect to the cathode of said other tube, whereby the anode and cathodeof said multi-grid tube are normally more positive respectively than theanode and cathode of said. other tube, a direct current potentialdivider including at least two impeders in shunt to said first directcurrent source, a connection between a point on said potential dividerbetween said two lastnamed impeders and the control grid of said othertube, a direct connection between the anode of the other tube and thescreen grid of the multigrid tube, means for applying signals to thecontrol grid of one tube, and means for deriving output from the anodeof one or the other tube.

2. In a locking circuit, two electron discharge tubes each having acathode, an anode and a control grid, one of said tubes also having ascreen grid, means for causing said one tube to be conductive whilecausing the other tube to be cut-oil, said means including a source ofdirect current potential connected between the anode and cathode of saidone tube with its positive terminal toward the anode of said one tube, aresistor in the connection between said source and the anode of said onetube, a resistor connecting a positive point on said source to the anodeof the other tube, connections to said source for maintaining thecathode of the other tube negative relative to the cathode of the fi sttube, a direct current potential divider includin series resistancesconnected indirectly across said source, a connection between a point onsaid divider between said series resistances and the control grid of theother tube such that a reduction of direct current potential on theanode of said one tube applies a more negative bias to the control gridof the other tube, means including a direct current connection betweenthe screen grid of the said one tube and the anode of the other tube forholding said screen grid at a relatively high positive direct currentpotential when said one tube is conductive and said other tube isnon-conductive and for materially reducing the potential on said screengrid when said other tube is conductive and said one tube isnon-conductive, and means for applying signal pulses to the control gridof said one tube, the arrangem nt being such that the potential on theanode of said screen grid tube varies with respect to a positive valueand the potential on the anode of said other tube varies plus and minuswith respect to a base value as said locking circuit is tripped.

ARTHUR E. CANFORA.

REFERENCES CITED The following references are of record in the file ofthis patent:

.UNITED STATES PATENTS Number Name Date 1,978,461 Hoover et al Oct. 30,1934 2,050,059 Koch Aug. 4, 1936 2,071,759 Minorsky Feb. 23, 19372,250,202 Matusita July 22, 1941 2,354,930 Stratton Aug. 1, 19442,431,591 Snyder, Jr., et al. Nov. 25, 1947 2,434,916 Everett Jan. 27,194.8

OTHER REFERENCES Electrical Counting (1943) by Lewis, The Mac- MillanCo., New York.

Time Bases, by O. S. Puckle, October 1943, John Wiley & Sons.

